The increasing market demand for wireless connectivity coupled with innovations in integrated circuit technology have motivated the development of wireless devices equipped with low cost, low power, and compact monolithic integrated radio transmitters, receivers, and transceiver systems with integrated antennas. Indeed, various types of wireless devices with embedded wireless systems have been developed to support wireless applications such as WPAN (wireless personal area network), WLAN (wireless local area network), WWAN (wireless wide area network), and cellular network applications, for example. In particular, wireless standards such as the 2.45 GHz ISM (Industrial-Scientific-Medical), WLAN 5.2/5.8 GHz, GPS (Global Positioning System) (1.575 GHz), PCS1800, PCS1900, and UMTS (1.885-2.2 GHz) systems are becoming increasingly popular for laptop computers and other portable devices. In addition, ultra-wideband (UWB) wireless systems covering 3.1 GHz-10.6 GHz band have been proposed as the next generation wireless communication standard, to increase data rate for indoor, low-power wireless communications or localization systems, especially for short-range WPAN applications. With UWB technology, wireless communication systems can transmit and receive signals with more than 100% bandwidth with low transmit power typically less than −41.3 dBm/MHz.
In general, wireless devices can be designed having antennas that are disposed external to, or embedded within, the housing of such wireless devices. For example, a portable laptop computer may have an external antenna structure mounted on a top region of a display unit of the laptop. Further, a laptop computer may have a card interface for use with a PC card having an antenna structure formed on the PC card. These and other external antenna designs, however, have many disadvantages including, e.g., high manufacturing costs, susceptibility of antenna damage, unsightly appearance of the portable device due to the external antenna, etc.
In other conventional schemes, antennas can be embedded within the device housing. For example, with portable laptop computer designs, antenna structures can be embedded within a display unit of the laptop computer. In general, embedded antenna designs are advantageous over external antenna designs in that embedded antennas reduce or eliminate the possibility of antenna damage and provide for better appearance of wireless devices. With embedded antenna designs, however, antenna performance can be adversely affected with wireless device housings having limited space and lossy environments. For instance, antennas that are embedded in the display unit of a laptop computer can experience interference from surrounding metallic components such as a metal display cover, a metallic frame of a display panel, etc, or other lossy materials in proximity to the embedded antenna structure, and must be disposed away from such objects and material.
As computing devices are made smaller with increasingly limited space, embedded antennas must be designed with more compact structures and profiles, while maintaining sufficient antenna performance. The ability to construct such antennas is not trivial and can be problematic, especially when antennas must be designed for wideband, multi-mode wireless applications. Indeed, although multi-band antennas can be designed with a plurality of separate radiating elements to enable operation over multiple operating bands, the ability to achieve suitable antenna performance over the different operating bands often requires relatively large size multi-band antenna structures, which may not meet the space constraints within the laptop computers or other wireless devise. This has motivated the need for low-profile, compact multiband, multi-standard embedded antenna frameworks, which are capable of covering a wide operating bandwidth for implementation with wireless devices to support multiple wireless systems/standards.